I was kind of curious about that myself. When I go back for another dyno run after I install the jet kit and muffler, I am going to ask why. They were busy when I went in there for the first dyno run and since they did not charge me, I was did not want to take up too much of their time.
I have seen that number too. I think the 76 horsepower is measured off the crank and not the rear wheel. Also, there can be a few hp variance from dyno to dyno. I have seen a few other dyno charts for the ZR-7 and they are all pretty close to the results I obtained.